1. Field of the Invention
This invention relates to an anti-mycoplasma agent comprising one or more of tropolone, its derivatives, which are represented by the following formula; ##STR2## (where in R.sub.1 is hydroxy, aliphatic acyloxy, arylacyloxy, arysulfonyloxy, carboxyalkyloxy or its ester, benzoylalkyloxy, alkenyloxy, 1,3-dihydro-3-oxo-1-isobenzofuranyloxy, (2-oxo-5-methyl-1,3-dioxol-4-yl)methyloxy or thiocyanato and R.sub.2 is hydrogen, halogen, hydroxy, alkyl or alkoxy) and their salts. Specifically, this invention relates to an anti-mycoplasma agent comprising one or more of tropolone, its derivatives such as O-acetyltropolone, O-benzoyltropolone, O-(p-toluenesulfonyl)tropolone, O-(1-carboxyethyl)tropolone, O-(tert-butyloxycarbonylmethyl)tropolone, O-(pivaloyloxymethyl)tropolone, O-(1-ethoxycarbonylethyl)tropolone, O-(benzoylmethyl)tropolone, O-allyltropolone, O-(1,3-dihydro-3-oxo-1-isobenzofuranyl)tropolone, 7-bromotropolone, O-{(2-oxo-5-methyl-1,3-dioxol-4-yl)methyl}tropolone, 7-methoxytropolone, 7-hydroxytropolone, 7-methyltropolone, and 2-thiocyanatotropone, their complex with heavy metals such as iron, copper, cobalt and nickel, their salts with metals such as calcium, magnesium, zinc and sodium and their salts with organic bases such as ethanolamine, n-propylamine, lysine and arginine.
Further, this invention relates to a compound represented by the following formula; ##STR3## (wherein R.sub.1 is 1-carboxyethyloxy, tert-butyloxycarbonylmethyloxy, 1-ethoxycarbonylethyloxy, 1,3-dihydro-3-oxo-1-isobenzofuranyloxy or (2-oxo-5-methyl-1,3-dioxol-4-yl)methyloxy).
2. Prior Art
Tropolone is a compound well known as bactericide and fungicide. It is prepared from tropone by the reaction with hydrazine and subsequent treatment of the resulting 2-aminotropone with an alkali or from cycloheptane-1,2-dione by the reaction with bromine and subsequent reduction of the resulting 3-bromotropone. It is also produced by some strain of the genus pseudomonas (J. Natural Products, vol. 43, No. 5, 592-594 (1980)). Its activity against bacteria and fungi has already been known (U.S. Pat. No. 3,448,155) but its activity against mycoplasma has not yet been found at all. With regard to derivatives of tropolone, acetyltropolone, benzoyltropolone and so on have already been synthesized (J. Amer. Chem. Soc., 73, 828 (1951)).
Now tylosin is mainly used for the therapy of animal diseases caused by mycoplasma. However, the emergence of tylosin-resistant mycoplasma is a present serious problem. Therefore, such anti-mycoplasma agent as effective against tylosin-resistant mycoplasma has been long desired.